Log every SQL query to database in Rails

Question

I want to save to a log file some SQL query rails performs, (namely the CREATE, UPDATE and DELETE ones) therefore I need to intercept all queries and then filter them maybe with some regexp and log them as needed.

Where would I put such a thing in the rails code?

Answer 1

SQL Server? If so...

Actually, I'd do this at the SQL end. You could set up a trace, and collect every query that comes through a connection with a particular Application Name. If you save it to a table, you can easily query that table later.

Answer 2

SQL logging in rails - In brief - you need to override ActiveRecord execute method. There you can add any logic for logging.

Answer 3

Here a simplified version of what c0r0ner linked to, to better show it:

connection = ActiveRecord::Base.connection
class << connection
  alias :original_exec :execute
  def execute(sql, *name)
    # try to log sql command but ignore any errors that occur in this block
    # we log before executing, in case the execution raises an error
    begin
        file = File.open(RAILS_ROOT + "/log/sql.txt",'a'){|f| f.puts Time.now.to_s+": "+sql}
    rescue Exception => e
      ;
    end
    # execute original statement
    original_exec(sql, *name)
  end
end

Answer 4

If you are using mysql I would look into mysqlbinlog . It is going to track everything that potentially updates data. you can grep out whatever you need from that log easily.

http://dev.mysql.com/doc/refman/5.0/en/mysqlbinlog.html

http://dev.mysql.com/doc/refman/5.0/en/binary-log.html